Combination heating and humidifying system

ABSTRACT

A normally shut off, electrically operated, spray humidifier is provided for humidifying a flow of air produced by a furnace blower controlled by a heat-responsive switch that is independent of the thermostat circuit which controls the furnace burner. The humidifier is connected in the thermostat circuit through a normally open switch that is closed only when a sail, operatively connected with the switch, is moved by the flow of air produced by the blower. Consequently, the humidifier does not start to operate until the flow of air begins, but the humidifier is shut off when the burner is turned off.

United States Patent 1191 Cofiman 1 Dec. 4, 1973 [5 COMBINATION HEATINGAND 3,247,839 4/1966 Lindberg 126/113 HUMIDIFYING SYSTEM [75] Inventor:John R. Coffman, Scottdale, Pa. Jr. [73] Assignee: Lewbill Industries,Inc., Scottsdale, AttorneyBrown, Murray, Flick & Peckham 22 Filed: Nov.16, 1971 [571 ABSTRACT A normally shut off, electrically operated, sprayhu- [211 App] 199258 midifier is provided for humidifying a flow of airproduced by a furnace blower controlled by a heat- 52 US. Cl 126/113,165/20, 236/11, responsive Switch that is independent of the thermo-236/44 C stat circuit which controls the furnace burner. The hu- 511111. C1 F24f 3/14 midlfier is connected in the thermostat oirouitthrough [58] Field 61 Search 236/11, 44 L, 44 A; a normally p Switchthat is closed y when a sail, 126/113; 165/20 operatively connected withthe switch, is moved by the flow of air produced by the blower.Consequently, [56] References Cit d the humidifier does not start tooperate until the flow 3,262,444 7/1966 Davidson 3 ,635 ,2 l 0 of airbegins, but the humidifier is shut off when the UNITED STATES PATENTSburner is turned off.

1/1972 Morrow 1 Claim, 2 Drawing figures [[0 2 THERMOSTAT L 15HUMIDISTAT 1 l BLOWER SWITCH 12 I6 PLENUM l l p HUMIDIFIER SAIL SWITCHCOMBUSTION 8 CHAMBER l l 8 n T J PATENTEB DEC 4 I975 THERMOSTAT l [7;]

BLOWER SWITCH STACK HUMIDIFIER COMBUSTION CHAMBER E; HUMIDISTAT Fly. 2

INVENTOR JOHN R. COFFMA/V W W W ATTORNEYS COMBINATION HEATING ANDHUMIDIFYING SYSTEM The most efficient way of humidifying the atmospherein an area heated by a forced warm air furnace is to spray a fine mistof water into the warm air leaving the furnace. The water mist isimmediately evaporated by the warm air and does not collect in dropletsin the furnace or the ducts, which would cause corrosion. Suchcollection of water will occur, however, if the spray is turned onbefore the air from the furnace is warm enough to evaporate the water orif the spray continues after the burner has shut off and the continuingflow of air from the blower cools down to the point where it no longerevaporates the water.

It is among the objects of this invention to provide a heating andhumidifying system in which the humidifying water is introduced in thefonn of a spray, in which the spray is not turned on until the air fromthe furnace is warm enough to evaporate the water immediately, in whichthe spray is turned off before the air from the furance cools enough tostop evaporating the water, and which is simple and does not requireelectric relays.

The preferred embodiment of the invention is illustrated in theaccompanying drawings, in which FIG. 1 is a somewhat diagrammaticsection through a furance provided with my humidifying system; and

FIG. 2 is a wiring diagram of the heating and humidifying systems.

Referring to the drawings, a warm air furnace I having a cold air inletduct 2 and a warm air outlet duct 3 is provided with the usualcombustion chamber 4, around which air from the inlet duct is circulatedby an electric blower 5 so that the air can pick up heat from thecombustion chamber and become warmed by it before reaching the outletduct. The forced flow of air through the furnace is continuous as longas the blower operates. The combustion chamber burner 6 may be gas-firedor oil-fired, but in either case the fuel to the burner normally isturned off but is supplied to the burner whenever an electricallyoperated valve 7 is opened or an electric fuel pump is operated. Thecontrol of the burner is through wires 8 and 9 from the usual roomthermostat 10, which may be operated by a transformer 11 connected intothe house circuit wires 12 and 13. The thermostat normally is open, butas the surrounding area starts to cool, the thermostat closes tocomplete the circuit to the burner.

The blower operates independently of the thermostat because it is notconnected into the thermostat circuit. It is operated directly by thehouse circuit and is controlled by a normally open heat-responsiveswitch 15, usually in the plenum of the furnace. This switch, shown inwire 12, does not close until the warm air leaving the furnace reaches apredetermined elevated temperature, and it will not reopen until thetemperature drops a considerable number of degrees. When the switchcloses, the blower comes on and produces a flow of air through thefurnace. This flow will continue, even after the burner turns off, untilthe furnace cools down to the point where the blower switch opens again.

The heating system that has been described is conventional. The furnacealso may be provided with additional safety switches and circuits toprevent overheating and to shut off the fuel in case of failure ofignition.

It is a feature of this invention that the warm air from vided with anovel control. The humidifier 16 includes a normally closed solenoidvalve that controls delivery of water to the spray nozzle 17, so thehumidifier functions only while this valve is open. The humidifierobtains its electric current only from the thermostat circuit, such asthrough wires 18 and 19 connected to wires 8 and 9, repsectively.However, if the humidifier were to be turned on every time thethermostat called for heat, there would be a considerable accumulationof water in the furnace and the ducts before the air from the furnacereached a high enough temperature to evaporate the spray. This highlyundesirable condition is preventied in accordance with this invention byproviding means for preventing the humidifier from being turned on untilthe furnace is hot enough to evap orate the spray. This is accomplishedby connecting a normally open switch 20 in the humidifier circuit, suchas in wire 18, and mounting this switch either in the warm air duct orthe cold air return duct, preferably the latter. The switch contains amovable contact 21 (FIG. 2) that is actuated by a long vane or sail 22pivotally mounted near one end in the switch housing. This sail extendsthrough an opening in the adjoining duct and a considerable way acrossthe duct.

As long as the blower is not operating, so that there is no forcedcirculation of air, the sail remains in its switch-open position shownin full lines in FIG. 1. On the other hand, as soon as a flow of airthrough the duct is produced by the blower, the downwardly flowingcurrent of air impinging upon the sail causes it to swing down and closethe switch, thereby completing the circuit to the humidifier to turn iton. It will be observed that this cannot occur until the air is movingand leaving the furnace warm enough to close the blower switch 15, whichis set to close at a temperature high enough for the air to evaporatethe water sprayed into the furnace by the humidifier.

The circuit that includes the humidifier and the sail switch can alsoinclude a conventional humidistat 24 that contains a normally closedswitch. In case the humidity of the atmosphere in the area served by thehumidistat starts to exceed the maximum for which the humidistat is set,the switch in the humidistat will open and thereby shut off thehumidifier even though the sail switch is still closed.

It will be seen that with this invention the humidifier is turned onwith the blower, but not by the blower, and turned off with the burner.Consequently, humidification does not start until the furnace is hotenough to take care of it properly, and it stops the moment heat inputto the furnace is stopped, so no humidifying takes place while thefurnace is cooling down. In other words, the humidifier is not on whilethe furnace is warming up or while it is cooling off. Also, if theblower should fail to shut off when it is supposed to, there is nodanger of the humidifier continuing to operate, as there is when ahumidifier is wired into the blower circuit. The circuits are simple,safe and avoid the use of relays.

Another advantage is that when the furnace is in an air conditioningsystem, the blower can operate without turning on the humidifier becausethe burner will remain ofi.

According to the provisions of the patent statutes, I have explained theprinciple of my invention and have illustrated and described what I nowconsider to reresent its best embodiment. However, I desire to have itunderstood that, within the scope of the appended shut off electricallyoperated spray humidifier for humidifying said flow of air, an electriccircuit for the humidifier deriving electric current from only thethermostat circuit for operating the humidifier, said humidifier circuitincluding a normally open switch, and a sail actuated by said flow ofair for closing said last- ,mentioned switch to turn on the humidifierafter the blower starts, whereby the humidifier starts to operate whensaid flow of air starts and stops when the burner is turned off.

1. The combination with a heating system having an electrically operatedfurnace burner for heating air, a thermostat circuit connected to theburner for turning it on and off, an electrically operated blower, and aheat-responsive switch adjacent the burner electrically connected withthe blower for turning it on and off idependently of the thermostatcircuit to produce a flow of air; of a humidifying system comprising anormally shut off electrically operated spray humidifier for humidifyingsaid flow of air, an electric circuit for the humidifier derivingelectric current from only the thermostat circuit for operating thehumidifier, said humidifier circuit including a normally open switch,and a sail actuated by said flow of air for closing said last-mentionedswitch to turn on the humidifier after the blower starts, whereby thehumidifier starts to operate when said flow of air starts and stops whenthe burner is turned off.